The present invention generally relates to disk drives employed in computer systems, and more particularly, to a disk drive arrangement that provides for the enhanced clamping of one or more storage disks to a disk drive spindle.
Disk clamps are utilized in computer disk drives to maintain the desired positioning of one or more disks relative to a drive spindle. If disk slippage occurs after assembly, and particularly after the disks are formatted (e.g., after burn-in of servo tracks), the read/write capabilities of the system may be severely compromised.
As such, much attention has been directed to the provision of effective disk clamping assemblies. See e.g., U.S. Pat. No. 5,486,962 to Boutaghou; U.S. Pat. No. 5,490,024 to Briggs et al.; U.S. Pat. No. 5,517,374 to Katakura et al; U.S. Pat. No. 5,548,457 to Brooks et al; U.S. Pat. No. 5,592,349 to Morehouse et al; U.S. Pat. No. 5,663,851 to Jeong et al.; U.S. Pat. No. 5,694,269 to Lee; U.S. Pat. No. 5,712,746 to Moir et al; U.S. Pat No. 5,790,346 to Fletcher; U.S. Pat. No. 5,828,519 to Sasa; and U.S. Pat. No. 5,847,900 to Iwabuchi. As reflected by the art, several interrelated design considerations exist.
Of particular importance, it has been recognized that the localized provision of clamping forces to a disk clamp, and in turn to the clamped disks, may result in undesirable disk flatness distortion. As such, effective clamping assemblies should provide for the relatively uniform application of clamping forces. Relatedly, effective clamping assemblies should provide for a highly predictable clamping force. It has also been recognized that effective clamping assemblies should allow for ready assembly and provide consistent assembly positioning in large-scale production operations. For example, effective clamping assemblies should provide for precise and repeatable positioning of the clamped storage disks, both axially and in lateral orientation. Such positioning is important for accurate functioning of read/write heads.
In addition to the noted criteria, the present inventor has recognized a number of other design considerations that will become increasingly important as data storage capacity requirements per unit space continue to increase.
Accordingly, a primary objective of the present invention is to provide a disk drive apparatus having a clamping arrangement that maintains disk flatness, provides reliable clamping forces, and may be readily employed in an assembly operation to afford repeatable disk positioning. Additional advantages may include one or more of the following:
improved disk resonance attenuation;
reduced disk drive servicing requirements;
reduced contaminant generation;
improved ease-of-assembly with low part count and inventory; and
convenient implementation into existing disk drive systems.
One or more of the above-noted objectives and advantages may be realized in the present invention by virtue of an inventive disk clamp/drive spindle arrangement. More particularly, a disk drive apparatus is provided that comprises a drive spindle and at least one axial-restraining member fixedly interconnected to the drive spindle about an outer periphery thereof. The axial restraining member(s) may be integrally defined with the outer periphery of the drive spindle and defined to arcuately extend around only a limited portion of a cylindrical drive spindle. The drive spindle extends through a central opening of one or more disks which are disposed about the drive spindle. The disk clamp includes a central aperture which is positionable over a top end of the drive spindle at a predetermined, axially-fixed location relative to the drive spindle and disk(s) so as to engage and provide a desired clamping force to the top disk. Such predetermined axial positioning and clamping force is maintained by a mechanical interface between the disk clamp and the axial restraining member(s).
In one aspect of the invention, the disk clamp includes a bottom side having an outer surface adapted for substantially uniform application of the clamping force to the top disk. In this regard, such outer clamping surface may be provided for engaging the top disk of a disk stack in a flush, face-to-face manner about clamping contact region (e.g. an annular region). The clamping surface of the disk clamp may be preferably configured for substantially continuous engagement with the top disk about a circular engagement region.
In another aspect of the present invention, the axial restraining member(s) is provided to project outwardly from the outer periphery of the drive spindle, thereby defining a corresponding lip. Such lip is disposed to restrainably engage an inner surface located on the top side of the disk clamp. In this regard, such inner, restrained surface may be defined by at least one or more projection(s) extending inwardly at the central aperture of the disk clamp. The projection(s) may be provided to arcuately extend around only a limited portion of the central aperture.
Preferably, a plurality of outwardly extending, axial restraining members are circumferentially spaced about and integrally defined with the outer periphery of the drive spindle, and a plurality of inwardly extending projections are spaced about the central aperture of the disk clamp, wherein one or more of the restraining members is engageable with at least one of the projections to maintain predetermined axial positioning of the disk clamp and attendant disk clamping forces. Most preferably, a plurality of axial restraining members are spaced about the drive spindle to allow for the passage of a corresponding plurality of inward disk clamp projections therebetween, thereby facilitating ready assembly/disassembly of the apparatus.
In a further related aspect of the present invention upon interconnection of the disk clamp and drive spindle the disk clamp may downwardly deflect, or bowed, between an outer bottom disk clamping surface engaging a top disk and an inner top disk clamp surface engaging the axial restraining member(s) provided about the drive spindle. Such deflection readily and reliably provides a desired clamping force upon clamping of the storage disk(s) to the drive spindle via the disk clamp. Preferably, the inner surface on the top side of the disk clamp engages a plurality of axial restraining member spaced about the circumference of the drive spindle, and the outer surface on the bottom side of the disk clamp engages the top storage disk about a continuous annular ring, with the disk clamp downwardly deflected, or bowed, therebetween (e.g. so as to define a shallow dish or ring configuration).
The disk clamp may assume a variety of cross-sectional configurations. By way of example, the disk clamp may be substantially flat, or plate-shaped, wherein the clamp may be deflected into a shallow disk or ring configuration upon assembly. In another arrangement, the disk clamp may be fabricated to define an upwardly-oriented, frusto-conical configuration prior to interconnection with the drive spindle.
In one arrangement, a disk drive is provided which includes a cylindrical drive spindle and a plurality of stacked disks disposed thereabout on a lower shelf of the drive spindle. One or more spacer members may be provided in the stack therebetween each storage disk. A plurality of axial restraining members are defined about a top end of the drive spindle by outwardly extending tabs which in turn define inwardly extending recesses therebetween. Such tabs may be integrally formed with the top end of the spindle. Correspondingly, a plurality of projections may be integrally defined at the central aperture of a circular disk clamp (e.g. plate-shaped) by inwardly extending tabs. Such tabs serve to define outwardly extending recesses therebetween. The plurality of tabs and recesses at the top end of the spindle and of the disk clamp, respectively, are sized and shaped so that the disk clamp may be positioned over the top end of the drive spindle and axially advanced with the application of an axially directed loading force so that the disk clamp tabs pass between and axially beyond the drive spindle tabs. The disk clamp may then be rotated about the top end of the spindle and the loading force released to establish restraining engagement between the spindle tabs and disk clamp tabs. As will be appreciated, the axial location of the tabs on the drive spindle disposes the central aperture of the disk clamp at a predetermined desired position. Correspondingly, the axial height of the top disk of the disk stack (i.e. relative to the drive spindle) serves to position the outer rim of the disk clamp at a predetermined position, wherein the disk clamp may deflect to a predetermined desired extent upon assembly to reliably provide a predetermined clamping force. Of note, such clamping may be established free from any connecting members (e.g. screws) extending between the disk clamp and top shelf of the drive spindle.
A ring of apertures may also be provided through the disk clamp for aligned positioning over a corresponding ring of holes provided on a top shelf of the spindle. Such apertures and holes may be aligned upon interconnection of the disk clamp and spindle to receive balance weights therethrough. The access apertures in the disk clamp may be provided in arcuately offset relation to the recesses defined about at the central aperture of the disk clamp.
One of the more above-noted objectives and advantages may also be realized by an inventive method for interconnecting, or clamping, one or more disks to a drive spindle in a disk drive apparatus. The inventive method comprises the initial step of disposing one or more disks about a drive spindle. Such step may include consecutively positioning a central opening of each disk in aligned relation with a drive spindle and axially advancing the disk into position (e.g. with a corresponding axial spacer between each stacked disk). The inventive method further includes positioning a disk clamp about the drive spindle and axially advancing the disk clamp relative to the drive spindle. A load force is applied to the disk clamp, wherein upon engagement between the disk clamp and a top storage disk a clamping force is applied by the disk clamp to the top disk. In order to maintain the application of such clamping force, the method further includes axially restraining the disk clamp via restraining engagement with one or more restraining members interconnected about the drive spindle. The axial restraining member(s) may be integrally defined with the outer periphery of the drive spindle and defined to arcuately extend around only a limited portion of a cylindrical drive spindle.
In conjunction with the application of a load force, the inventive method preferably comprises the step of deflecting the disk clamp. Such deflection may entail bowing a disk clamp from a substantially flat, or plate-like, configuration to a shallow dish or ring configuration. In another arrangement, application of a load force may entail the deflection of a disk clamp having an upwardly oriented, frusto-conical configuration prior to deflection. Loading forces may be advantageously provided by assembly tooling, wherein the tooling may axially restrain an outer rim of the disk clamp (e.g. about an outer annular ring-shaped region) while axially displacing a central region of the disk clamp surrounding the central aperture (e.g. about an inner annular ring-shaped version). The axial displacement causes the disk clamp to slightly deflect, or bow, from an inactive, unloaded state to an active, loaded state. Such deflection is preferably maintained solely by the assembly tooling during disk clamp positioning relative to the drive spindle. As such, an external loading force may be advantageously provided free from force transfer to other disk drive components (e.g. the drive spindle) during assembly operations. When the bowed disk clamp is in the desired position relative to the drive spindle, the assembly tooling may be adapted for selective release of the restraints on the outer rim and central region of the disk clamp, thereby loading the disk clamp in its deflected, or active state to the drive spindle and disk stack.
In conjunction with the axial restraint of the disk clamp (e.g. in the central region thereof), the inventive method may further comprise the step of rotating at least one of the drive spindle and disk clamp relative to the other. For example, the above-noted assembly tooling may rotate prior to release of the outer and inner axial restraint of the disk clamp. As will be appreciated, axial restraint of the disk clamp on the drive spindle may be achieved by aligning outwardly projecting tabs provided on the drive spindle with inwardly projecting tabs provided on the disk clamp, axial movement of the disk clamp is restrained by the drive spindle tabs after assembly.
Additional aspects and advantages of the present invention will become apparent upon consideration of the drawings and detailed description which follow.